Exit selecting system



Sep. 7, 1965 P. D. scHwARZ ETAL 3,205'479 EXIT SELECTING SYSTEM Filed Aug. 15, 1962 2 Sheets-Sheet 1 I I NORTH STREET -DETECTOR GARAGE'W I J |o 9 L, 2 BEST EXIT BEST EXIT 3 WEST STREET EAST STREET CONTROL /WEST STREET EAST STREET I I APPARATUS l l l SOUTH STREET INVENTORS PDSCHWARZ AND R.A.OVERMYER THEIR ATTORNEY 2 Sheets-Sheet 2 P. D. SCHWARZ ETAL EXIT SELECTING SYSTEM Sept. 7, 1965 Filed Aug. 13, 1962 INVENTORS P.D .SCHWARZ AND By R.A.ovERMYER THEIR ATToRNEY United States Patent O 3,2%,479 `EXHT SELECTENG SYSTEM Peter D. Schwarz, Rochester, and Richard A. Overmyer, Pittsford, N.Y., assignors to General Signal Corporation Filed Aug. 13, 1962, Ser. No. 216,609 6 Clairns. (Cl. 3430-51) This invention relates to vehicular exit selccting systems and more particularly to a system. for routing Vehicles from an enclosed area onto a street having a minimum of traflic congestion.

Many systems have been devised for internal routing of traffic entering enclosed areas such as garages. Heretofore, however, where the enclosed area has exits opening onto more than one street, means have not been devised for internal routing of the departing Vehicles to exits leading to the street having least traffic congestion. This often results in long de'lays for departing Vehicles prior to entering the stream of traffic flow, as well as increasing congestion on .an already congested street. lt would be d'esirable in these instances to provide some form of internal traflic routing to exits leading to the street where .traflic cong-estion is at a minimum. This can best be acc-omplished 'by providing an automatic internal traflic routing -system which is dependent upon relative tnaflic con-gestion in the streets leading from the exits. Such system can be used `to sense street traffic parameters and responsively actuate internal routing indicators. A system of this sort can be applied with great advantage not only to garages but ;also to parking lots, drive-in theaters, Vehicular loading and delivery areas, shopping centers or any other form of parking area used by Vehicles and having a plurality of exits.

The apparatus for sensing trafi'ic conditions on the streets leading from the enclosed area exits is concerned with providin'g 'a measure of traffic 'lane oecupancy; that is, the lpercentage of any given period of time during which ya traffic 'lane is Vehicle-occupied. 'For example, when no Vehicles pass along the l-ane, traflic occupancy is zero. However, occupancy approaches 100% when Vehicles are almost bumper-to-bumper along the lane. Thus, the parameter of lane occupancy is used herein to provide 'an indication of street traffic congestion.

It should be noted that traflic Volume could be sensed in place of occupancy. This parameter, which may be defined as the number o-f Vehicles passing a particular location per unit time would pro'bably be more useful than that of l'ane occupancy where the parking facility has exits opening onto a plurality of high speed highways or streets having few intersections and hence little likelihood of traflic stoppages. Thus, the invention can be 'used in conjunction with measurement of either afore- Vmentioned trafiic parameter.

congestion for routing trafiic departing from the parking ice the enclosed area to exits leading to the street having least percentage of lane occupancy.

Other objects and advantages of the invention will become apparent from the specification, the drawings and the appended claims.

In the drawings:

FIG. 1 is a schematic ill-ustration of an enclosed parking facility utilizing the present invention, having an exit opening onto each of two streets.

`FIG. 2 is a block diagram of an exit selecting system constructed in accord'ance with the invention.

Referring now to PIG. 1, a parking facili-ty such as the ground floor of a garage 1 is shown having an exit 2 opening onto a street design-ated West Street, and a second exit 3 opening onto a street designated East Street. Although only one exit opening onto each of two `streets is shown for simplicity, the system will operate equal'ly as well with a facility having any number of exits 'opening 'onto any number of streets. 'Both East and West Streets are shown intersecting 'a second pair of streets design'ated North Street and South Street. Vehicle presence detectors 4 and 5 are located on West Street at the intersection with North Street and South Street respectively, while vehicle detectors 6 and 7 .are located on East Street at the intersections with North Street and South Street respectively. The outputs 'of Vehicle detectors 4, 5, 6 and 7 are 'applied to control apparatus 8 which in turn is connected to a pair of signs 9 and 10 indicating Best Exit East Street and Best Exit West Street respectively.

Vehicle presence detectors 4, 5, 6 and 7 may be ultrasonic detectors such as type SVDS-PD Vehicle Presence Detector described in lPamphlet 1060, revised January 1962, entitled Expressway Surveillance Equipment, and available 'from the instant assignee. I-Iowever, any form of vehicle presence detector producing an electrical output indicative of traffic congestion is useab'le with the present invention. Each detect-or senses Vehicles passing or standing beneath the detector, which, in the case of u-ltrasonic detectors, is preferably mounted overhead, although 'other forms of mounting -canfialso be used. Detection of Vehicles causes control apparatus 8 to produce an energizing Voltage which illumin'ates sign 9 or 10 depending upon relative traffic congestion on East and West streets. This enables drivers to select exits which will lead them onto the streets having the least amount of traffic congestion. The method by which this result is acc-omplished is discussed in connection with FIG. 2.

Turning now to FIG.2, vehicle sensors 4, 5, 6 and 7 are shown applying signals to control apparatus 8, shown dotted, which in turn energizes sign 9, sign 10 or neither sign, depending upon traiic conditions on West Street and East Street of PIG. 1. Control apparatus S, which compares lane occupancies lsensed by all its associated Vehicle detectors, comprises volume occupancy traffic Computers 11, 12, 13 and 14 receiving inputs from vehicle detectors 4, 5, 6, and 7 respectively. Each of the Volume occupancy Computers, such as type ES l0(}-VO described in the aforementioned Pamphlet 1060, provides a voltage indication of the precentage of time pavement is occupied by Vehicles as sensed by the detector connected to the computer, although if an indication of traffic volume is required, a voltage Proportional to the number of Vehicles passing its associated detector can be supplied by the same Volume occupancy computer. Outputs of Computers 11, 12, 13 and 14 are applied to level monitors 15, 16, 17 and 18 respectively. Each of the level monitors, such as type ES-lOO-LM described in the aforementioned Pamphlet 1060, produces an output consisting of one of a number of fixed voltage levels dependng upon the amplitude of applied Voltage. The level monitors used in PIG. 2 are shown having three outputs indicated low, medium and high, although any number of voltage levels may be used. In the embodiment shown in FIG. 2, the low and medium terminals of level monitor 15 are connected together to provide an input to a first terminal a of an AND gate circuit 19. The low and medium output terminals of level monitor 16 are connected together and provide an input to a second terminal b of AND circuit 19. The low and medium output terminals of level monitor 17 are connected together to provide an input to a first terminal a' of a second AND gate circuit 20, and the low and medium output terminals of level monitor 18 are connected together to provide an input to a second terminal b' of AND circuit 20. The high output terminals of the level monitors are connected together and provide inputs to third terminals c and c' of AND circuits 19 and 20 respectively. A power supply 21, of suificient output to energize signs 9 and 10, provides inputs to fourth terminals d and d' of AND circuits 19 and 20 respectively.

In operation, it is obvious that in order to illuminate sign 10, an input voltage must be applied to all four inputs of AND circuit 19, while to illuminate sign 9 an input voltage must be applied to all four inputs of AND circuit 20. For this condition to occur, at least one level monitor of either pair of monitors 15 and 16 or 17 and 18 must produce a high output voltage and both level monitors of .the other pair must produce either low or medium output voltages.

Thus, assume there are three levels of lane occupancy, low, medium and high, each of which causes a low, medium or high output voltage to be produced by the level monitor associated with the vehicle detector sensing occupancy. If none of the vehicle det-ectors sense high trafiic occupancy, neither AND circuit receives an input at its third terminal and correspondingly neither sign 9 nor 10 is energized. Drivers are thus free to select either exit 2 or exit 3 (shown in FIG. 1) since they will easily be able to enter the flow of traffic on either East or West Street. Now, assume a vehicle detector, such as detector 5, senses a high percentage of occupancy. Level monitor 16 thus produces a high output voltage, forming an input for the third terminals c and c' -of AND circuits 19 and 20. If detector 6 then senses low or medium occupancy and detector 7 senses low or medium occupancy, AND circuit 20 will receive'input voltages on all its input terminals, thereby illuminating sign 9 which indicates to drivers in the parking facility that exit 3 Will enable them to enter the flow of street trafiic more quickly and easily than exit 2. It should here be noted that if either detector 6 or 7 senses high occupancy levels, either input terminal a' or b' respectively of AND circuit 20 will not be energized, and consequently sign 9 will not be energized. .In such iustance, neither exit is relatively more advantageous, and drivers remain free to select either exit at their own volition. The circuit operates in similar fashion for other levels of occupancy sensed by the vehicle detectors. For example, if high occupancy is vsensed by detector 6 or 7, and detectors 4 and each 'sense either low or medium occupancy, sign will be illuminated, indicating to drivers in the parking facility that exit 2 will enable them to enter the flow of street traflic more quickly and easily than exit 3.

It should be obvious to those skilled in the art that the circuit` can be elaborated upon by compan'son of lanes having the lowest percentages of occupancy. Furthermore, the circuit can be expanded to meet the requirements of a parking facility having any number Vof exits opening onto any number of streets. The circuit can also be elaborated upon to indicate to drivers in the parking facility the best exit for heading in the general direction in which the driver intends to travel. The invention therefore provides a simple, convenient and reliable means for directing drivers to the best exit from an enclosed area containing Vehicles and having multiple exits, depending upon tratfic conditions in the streets leading from the enclosed area.

Having described an exit selecting system as one specific embodiment of the present invention, it is to be expressly understood that this form is selected to facilitate in disclosure of the invention rather than to limit the number of forms for which it may assume; various modifications, adaptations and alterations may be applied to the specific form shown to meet requirements of practice, without in any manner departing from the spirit or scope of the invention.

What we claim is:

1. An exit selecting system for a vehicular parking facility having exits opening onto a plurality of streets comprising vehicle presence detecting means on each of the streets for sensing lane occupancies, means coupled to each of the vehicle presence detecting means for selectively energizing one of a plurality of output terminals in accordance With sensed lane occupancy, indicating means for internally routing departing trafic within the parking facility, and circuit means coupled to the output terminals for controllably coupling energy to the indicating means, thereby directing trafiic departing from the parking facility to exits leading to the streets having a percentage of occupancy below a predeterrnined level when percentage of occupancy of any -of the vstreets increases beyond a predetermined level.

2. An exit selecting system for a vehicular parking facility having exits opening onto a plurality of streets comprising vehicle presence detecting means on each of the streets for sensing traffic, means coupled to each of the vehicle presence detecting means for energizing one of a plurality of output terminals in accordance with sensed traffic volume, indicating means for internally routing departing trafiic within the parking facility, and circuit means coupled to the output terminals for controlling energy applied to the indicating means in order to direct trafiic departing from the parking facility to exits leading to the streets carrying less than a predetermined level of traffic volume when traffic volume on any of the streets increases beyond a predetermined level.

3. An exit selecting system for a vehicular parking facility having exits opening onto a plurality of streets comprising vehicle presence detecting means on each of the streets for sensing lane occupancy, level monitor means operatively coupled to each of the vehicle presence detecting means for selectively energizing any one of a plurality of output terminals, said one output terminal being energized in accordance with lane occupancy as sensed by said each vehicle presence detecting means, indicating means consisting in separate portions thereof for internally routing tratfic departing from the parking facility, and switching means coupled to the level monitor means output terminals for energizing the indicating means, said switching means being comprised of a plurality of AND gates, each said AND gate coupling energy to a separate portion of the indicating means when the detecting means on any street senses a relatively high level of lane occupancy and the detecting means on any other street simultaneously senses a relatively low level of lane ocupancy.

4. The exit selecting system of claim 3 wherein Said switching means is further comprised of means coupling a first output terminal of each of said level monitor means jointly to each of said AND gates, means coupling a second output terminal of each of said level monitor means coupled to the presence detecting means on one street to a first of said AND gates, and means coupling a second output terminal of each of said level monitor means coupled to the presence detector means on another street to a second of said AND gates.

5. An exit selecting system for a vehicular parking facility having exits opening onto a plurality of streets comprising vehicle presence detecting means situated on each of the streets for sensing lane occupancy, AND gating means, circuit means coupling each of the vehicle presence detecting means to, said AND gating means for selectively providing discrete output voltages to said AND gating means, said discrete voltages being selected in accordance with lane occupancy as sensed by said each vehicle presence detecting means, and indicating means consisting in separate portions thereof for internally routing trafic departing from the parking facility, said AND gating means coupling energy to a separate portion of the indieating means When the detecting means on any street senses a relatively high level of lane occupancy and the detecting means on any other street simultaneously senses a relatively low level of lane occupancy.

6. An exit selecting system for a vehicular parking facility having exits opening onto a plurality of streets comprising vehicle presence detecting means situated on each of the streets for sensing traffic, Circuit means operatively coupled to each of the vehicle presence detecting means for selectively providing one of a plurality of separate output voltages, said one voltage bearing a relationship to traffic volume as sensed by said each vehicle presence detecting means, indicating means consisting in separate portions thereof for internally routing trafi'ic departing from the parking facility, and switching means coupled to the circuit means for energizing the indicating means, said switching means being comprised of a plurality of AND gates, each said AND gate coupling energy to a separate portion of the indicating means when the detecting means on any street senses a relatively high volume of traflic and the detecting means on any other street simultaneously senses a relatively low volume of traffic.

References Cited by the Examiner UNITED STATES PATENTS 2,980,887 4/61 Soderberg 340-35 NEIL C. READ, Primary Examiner.

THOMAS B. HABECKER, Examiner. 

1. AN EXIT SELECTING SYSTEM FOR A VEHICULAR PARKING FACILITY HAVING EXITS OPENING ONTO A PLURALITY OF STREETS COMPRISING VEHICLE PRESENCE DETECTING MEANS ON EACH OF THE STREETS FOR SENSING LANE OCCUPANCIES, MEANS COUPLED TO EACH OF THE VEHICLE PRESENCE DETECTING MEANS FOR SELECTIVELY ENERGIZING ONE OF A PLURALITY OF OUTPUT TERMINALS IN ACCORDANCE WITH SENSED LANE OCCUPANCY, INDICATING MEANS FOR INTERNALLY ROUTING DEPARTING TRAFFIC WITHIN THE PARKING FACILITY, AND CIRCUIT MEANS COUPLED TO THE OUTPUT TERMINALS FOR CONTROLLABLY COUPLING ENERGY TO THE INDICATING MEANS, THEREBY DIRECTING TRAFFICE DEPARTING FROM THE PARKING FACILITY TO EXITS LEADING TO THE STREETS HAVING A PERCENTAGE OF OCCUPANCY BELOW A PREDETERMINED LEVEL WHEN PERCENTAGE OF OCCUPANCY OF ANY OF THE STREETS INCREASES BEYOND A PREDETERMINED LEVEL. 